Creams: SOP for Water Activity Testing in Creams – V 2.0

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Creams: SOP for Water Activity Testing in Creams – V 2.0

Standard Operating Procedure for Water Activity Testing in Creams

Department Creams
SOP No. SOP/CRM/037/2025
Supersedes SOP/CRM/037/2022
Page No. Page 1 of 5
Issue Date 29/08/2025
Effective Date 03/09/2025
Review Date 29/08/2026

1. Purpose

The purpose of this Standard Operating Procedure (SOP) is to outline the process for measuring the water activity (aw) of cream formulations. Water activity is a critical parameter that influences the stability, microbial growth potential, and shelf-life of cream products. This SOP ensures that the water activity levels in cream formulations are within acceptable limits to ensure product quality and safety.

2. Scope

This SOP applies to all cream formulations developed within the Creams Department. It covers the methods for testing and controlling water activity in cream products to ensure that they remain stable and microbiologically safe throughout their shelf life.

3. Responsibilities

  • Formulation Development Team: Responsible for selecting ingredients that help control and stabilize water activity in cream formulations. They ensure that water activity is considered during the development phase.
  • Quality Control (QC): Responsible for conducting water activity tests on cream formulations during development and batch production. QC ensures that the cream’s water activity is within the specified range for stability and safety.
  • Quality Assurance (QA): Ensures compliance with this SOP, reviews the water activity test results, and approves the formulations for commercial production if the results meet the required specifications.
  • Production Team: Implements the water activity testing procedure during the production process and ensures that the final product has the required water activity levels.

See also  Creams: SOP for Weighing and Dispensing of Viscosity Modifiers for Creams - V 2.0

4. Accountability

The Head of Creams Manufacturing is responsible for overseeing the water activity testing process. The QA Manager is accountable for ensuring that the water activity tests are conducted in compliance with this SOP and that the results are documented and reviewed.

5. Procedure

5.1 Selection of Water Activity Testing Equipment

  1. Select an appropriate water activity meter to test the water activity in cream formulations. Common equipment used for this test includes:

    • Water Activity Meter: This device measures the equilibrium relative humidity in a cream sample and calculates the water activity based on the measurement.
  2. Ensure that the water activity meter is calibrated according to the manufacturer’s instructions before use. Calibration should be done regularly to ensure accurate measurements.

5.2 Sample Preparation

  1. Prepare the cream sample by ensuring it is homogeneous. The sample should be representative of the entire batch and taken from the final cream formulation.
  2. If necessary, allow the cream sample to equilibrate at room temperature to prevent any temperature-related fluctuations in water activity.
  3. Ensure that the sample size is appropriate for the water activity meter. Follow the manufacturer’s instructions for the sample quantity to be used.

5.3 Conducting Water Activity Testing

  1. Place the cream sample in the testing chamber of the water activity meter. Follow the manufacturer’s instructions for loading and sealing the sample.
  2. Set the water activity meter to the appropriate settings for cream samples. Start the test, allowing the sample to equilibrate in the chamber.
  3. Record the water activity value once the reading stabilizes. Water activity is typically measured on a scale from 0 (completely dry) to 1.0 (pure water).
  4. If the sample’s water activity is outside the specified range (e.g., above 0.85, which may increase the risk of microbial growth), take corrective actions such as modifying the formulation or drying the cream further.
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5.4 Water Activity Specification

  1. The target water activity range for cream formulations is typically between 0.60 and 0.85, depending on the type of cream and its intended use.

    • Moisturizing Creams: Water activity should be controlled to reduce the risk of microbial contamination while maintaining the cream’s intended sensory properties.
    • Anti-aging and Sunscreen Creams: A slightly lower water activity may be targeted to ensure product stability and shelf-life.
  2. If the water activity exceeds the acceptable range, investigate the formulation for potential causes and adjust accordingly, such as by modifying the emulsifier or adding stabilizers.

5.5 Stability Testing of Water Activity

  1. Conduct stability testing on the cream formulation to assess its water activity under different storage conditions. Stability testing should include:

    • Real-time Stability Testing: Store cream samples at normal conditions and measure the water activity at specified intervals over time.
    • Accelerated Stability Testing: Store cream samples at elevated temperatures to simulate long-term storage and measure any changes in water activity.
  2. Record all results from the stability testing and evaluate whether water activity levels remain consistent throughout the product’s expected shelf life.

5.6 Documentation and Reporting

  1. Document all water activity testing activities, including:

    • The type of water activity test conducted
    • The test equipment used and settings
    • The water activity values recorded for each sample
    • Any corrective actions taken if the water activity was outside the specified range
  2. Prepare a Water Activity Testing Report (Annexure-1) summarizing the test results and any necessary adjustments made to the formulation. This report should be reviewed and approved by the QA team before proceeding to production.
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5.7 Final Approval and Commercial Production

  1. Once the water activity is optimized and the formulation meets the required specifications, the cream is approved for commercial production.
  2. Ensure that water activity levels are monitored during production and batch release to maintain product quality and stability.
  3. Store all water activity testing data and documentation for future reference and regulatory compliance.

6. Abbreviations

  • QC: Quality Control
  • QA: Quality Assurance
  • GMP: Good Manufacturing Practices
  • API: Active Pharmaceutical Ingredient
  • aw: Water Activity

7. Documents

  1. Water Activity Testing Report (Annexure-1)
  2. Formulation Development Log (Annexure-2)
  3. Stability Testing Log (Annexure-3)

8. References

  • Good Manufacturing Practices (GMP) Guidelines – 21 CFR Part 211
  • International Conference on Harmonisation (ICH) Q7 – Good Manufacturing Practice for Active Pharmaceutical Ingredients
  • Cosmetic Science and Technology by D. A. Jones

9. SOP Version

Version: 2.0

10. Approval Section

Prepared By Checked By Approved By
Signature
Date
Name
Designation
Department

11. Annexures

Annexure-1: Water Activity Testing Report

Batch Number Test Method Water Activity (aw) Test Date Comments
12345 Water Activity Meter 0.72 29/08/2025 Pass, suitable for shelf life

Annexure-2: Formulation Development Log

Formulation Name Batch Number Ingredients Process Parameters
Moisturizing Cream 67890 Water, Glycerin, Hyaluronic Acid Mixing: 30 min, Temperature: 65°C

Annexure-3: Stability Testing Log

Test Type Test Date Water Activity Approval Status
Accelerated Stability 03/09/2025 0.73 Approved

Revision History:

Revision Date Revision No. Revision Details Reason for Revision Approved By
01/03/2024 1.0 Initial Version New SOP Creation QA Head
01/03/2025 2.0 Format Revision and Updates Standardization of Document QA Head
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